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Generation and Trapping of Ketenes in Flow.

ABSTRACT: Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95?% conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (E_a = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.

SUBMITTER: Henry C

PROVIDER: S-EPMC4464552 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Generation and Trapping of Ketenes in Flow.

Henry Cyril C Bolien David D Ibanescu Bogdan B Bloodworth Sally S Harrowven David C DC Zhang Xunli X Craven Andy A Sneddon Helen F HF Whitby Richard J RJ

European journal of organic chemistry 20150120 7

Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95 % conversion of EtO, <i>i</i>PrO, and <i>t</i>BuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be ...[more]

PMID: 26097406

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